Re: Fw: Help Needed: Midway Space Invaders w/ no sound

Now comes the fun part of backtracing and seeing where the voltage is
coming from. Too high a voltage (with no load) isn't going to blow the
fuse.

So I guess I'd just doublecheck all the voltages along the way. Should
be an easy one to spot.

Good luck!

Kurt
kmahan@xmission.com

> Ok, I pulled out the chip and measured the voltages. The one I'm concerned
> with the most is the audio voltage which was reading around 40 volts now!
> No wonder it was blowing away chips. I did measure 6.5 volts at one time
> (probably had something to do with pin 14 being shorted to ground), but
> right now it's pretty high. I can hear the coin slot counter going nuts
> too.
>
> I double checked all the pins where the chips goes to make sure nothing is
> shorted. I'm stumped. No fuses are blowing either. Help!
>
> Matt
>
>
> ----- Original Message -----
> From: "Mark Shostak (DOS)" <shostak@augustmail.com>
> To: <rasterlist@synthcom.com>
> Sent: Wednesday, December 11, 2002 8:44 PM
> Subject: Re: RASTER: Fw: Help Needed: Midway Space Invaders w/ no sound
>
>
> > Matt,
> >
> > You might consider checking your voltages with the chip removed.
> > You will at least be able to see if something else is holding down your
> V+,
> > or if there is something wrong with the supply itself.
> >
> > I've found shorted tantalum caps across the V+ supply before, but it's
> > always resulted in blowing the fuse in the bottom of the cabinet.
> >
> > You haven't really said how you determined the ics are bad.
> > Shorted pins? IIRC, 6 or 8 of the pins are supposed to be shorted
> (gnd/heat sink).
> >
> > Let us know what you find.
> >
> > -Mark
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Received on Thu Dec 12 12:17:14 2002